Alarm bells

The alarm had been ringing for twenty minutes, but nobody knew what it was for. "It has the rhythm of catastrophe," opined Jeremy, "but not the timbre." Jenny closed her eyes and raised a finger for quiet. "I heard something like this once before," she said after half a minute. "I think it was for 'man overboard'." We were not at sea, but we thought this got us closer. We decided to take five minutes to write down our ideas. Then we would reconvene and discuss. But it was very hard to think with all that noise going on, and by the time we came back together, it had stopped.